A computer network, often simply referred to as a network, is a group of interconnected computers and devices that facilitates communication among users and allows users to share resources. Adapters, switches and other devices are typically used during network communication for reading and writing data at mass storage devices.
Computing devices (or systems) use mass storage devices to store data. Data centers are commonly used to store large amounts of data for computing devices. Different storage options are available for computing devices to store data and retrieve data. For example, storage options include direct-attached storage (DAS), network attached storage (NAS), and storage area networks (SANs).
A DAS system typically includes a plurality of storage drives that are directly attached to a computing device (for example, a server) and is accessible via a host bus adapter (HBA). Common protocols used for DAS storage devices are SCSI (Small Computer Systems Interface), ATA (AT attachment), SATA (Serial ATA), SAS (Serial Attached SCSI) and others.
NAS is a file level storage that provides access to a plurality of computing devices. NAS typically uses network file sharing protocols, for example, NFS (Networked File System), CIFS (Common Internet File System) and others for storing and managing data at storage devices.
SAN is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and others, accessible to servers so that the devices appear like locally attached devices to an operating system of a computing device. A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices. SANs often utilize a Fibre Channel fabric topology, an infrastructure specially designed to handle storage communications. SANs may also use iSCSI (i.e. mapping SCSI over TCP/IP (Transmission Control Protocol/Internet Protocol), Fibre Channel over Ethernet (FCoE), FCP (Fibre Channel over SCSI), Hyper SCSI (i.e. SCSI over Ethernet) and other protocols for storing data at storage devices.
Fibre Channel protocol (FCP) is used to send a SCSI command or a task management request. When an initiator sends a command or request using Fibre Channel, then a FCP_CMD information unit (IU) is sent to a target. FCP_CMD IU indicates a task management function that may have to be performed. Examples of task management functions include aborting a task, aborting a set of tasks, resetting a target, resetting a logical unit identifier (LUN), a query to determine a state of a specific task, a bus reset operation and others. Continuous efforts are being made to efficiently perform task management functions.